When a new slab is poured and joined to an existing slab, bleeding occurs. What surface effect is expected?

• A. The surface will develop cracks
• B. The surface will cure with a smooth, uniform finish
• C. The surface will become slippery when wet
• D. The surface will lift along the joint

Answer: (A)

Bleeding brings water to the surface of freshly placed concrete as the mix cures. That water carries fine cement particles with it, forming a weak laitance layer at the top. When you pour a new slab against an existing one, the joint is restrained by the old concrete. As the slab continues to dry and shrink, those restrained surface zones experience tensile stresses. The combination of a softened, laitance-rich surface and restraint at the joint makes the surface prone to cracking along the joint.

So, the expected surface effect is cracks forming near the joint due to the interaction of bleeding, surface laitance, and shrinkage under restraint. The other options don’t capture this common consequence: bleeding doesn’t routinely produce a smooth, uniform finish; while a temporary slick feel can occur if there’s surface moisture, the characteristic defect under these conditions is cracking; lifting along the joint would indicate more than just surface cracking, involving separation or bond failure.